In the prior art, it is known to graft organically modified silanes onto a silica nanoparticle surface. Natural silica is covered with hydroxide groups, which are reactive with silanes having silanol or hydrolyzable groups, to bond the silane to the silica. Such silanes may carry a bonded organic radical such as an allyl group, an aminoalkyl group, or any of a variety of organic groups, which can change the surface characteristics of the silica.